The present invention relates to an improved system for controlling the ground speed of an off-road vehicle and, more specifically relates to an improved interconnected system for controlling the ground speed of lawn tractors, lawn and garden tractors and front-mount mowers having variable speed transmissions, such as hydrostatic or continuously variable transmissions.
It is well known to provide off-road vehicles, specifically lawn tractors, lawn and garden tractors, and front-mount mowers with systems for controlling their ground speed. Typically, variable speed transmissions such as hydrostatic transmissions or continuously variable transmissions utilized in off-road vehicles such as those listed above have used different combinations of hand and foot controls to select the direction of travel and to control the relative vehicle speed. Conventional off-road vehicle hand controls require that the operator remove at least one hand from the steering wheel to reach a control lever and to move it to the appropriate location. During the movement of the operator's hand from the steering wheel to the control lever, the operator is required to interrupt his concentration from the task he is performing with the vehicle in order to concentrate on moving his hand control to the proper position. Thus, with conventional hand controls, there is a tendency for operators to break their concentration and thereby to reduce productivity and operating comfort.
Another conventional system utilized to control the ground speed of the types of off-road vehicles mentioned above, includes a treadle pedal which is essentially a heel and toe forward and reverse control mechanism. With the treadle pedal control system, an operator normally places his foot on the pedal in such a way that the toe of the operator's foot would contact one portion of the treadle pedal and the heel would contact another portion. To drive the vehicle in the forward direction, the operator presses his toe forward thereby raising his heel off of the vehicle footrest. To change the movement to the direction to reverse or to slow it down, the operator would increase the pressure on his heel until the vehicle eventually came to the neutral position and to a complete stop; and then continue pressing his heel down toward the foot rest in order to produce vehicle movement in the reverse direction.
The conventional treadle pedal system has proved to have three significant problems, the first being operator discomfort which results from the fore-and-aft movement of the foot and the second, somewhat related to the first, being difficulty in modulating the vehicle's speed in either the forward or reverse direction because the conventional treadle pedal design requires that the operator keep his foot on both the forward control and reverse control portions of the pedal simultaneously. Additionally, because the operator's leg is suspended above the foot rest, with the foot located on a movable pedal without the foot maintaining contact with the foot rest thereby providing foot stability, vehicle speed control over rough terrain has proven most difficult.
A third and perhaps the most desirable ground speed control system developed to date for off-road vehicles is the dual pedal side-by-side system. The details of this system are disclosed in U.S. Pat. No. 4,759,417 dated Jul. 26, 1988 issued to Wanie et al. and commonly assigned to the assignee of the present application, the disclosure of which is hereby incorporated by reference. However, the side-by-side pedal location required the operator to use one foot to operate both the forward and reverse pedal and therefore, occasionally resulted in the wrong pedal being pressed for the direction the operator intended to have the vehicle move.
Specifically, in the two pedal side-by-side system, the two pedals are operated by the right foot. Each of the pedals when pushed moves through a similar forward arc. The main distinguishing feature between the reverse speed control pedal and the forward speed control pedal is that the reverse speed control pedal is located to the right of the forward speed control pedal. Both pedals occasionally require that the right foot and leg be lifted and the foot placed on the correct pedal in order to move the vehicle in the desired direction.
This side-by-side relationship is not as natural for an operator to relate to forward and reverse as are forward and reverse position pedals, since the operator moves his foot through a similar arc for both forward and reverse vehicle movement. Consequently, it may sometimes be difficult for an operator to feel which pedal his foot is engaging without looking.
An additional problem with present control systems is that they generally rely on a spring-loaded mechanism to return the variable speed or hydrostatic transmission to neutral. Frictional resistance in the lever controls or pedals and the linkages between the lever control or pedals and the variable speed transmission which may be caused by dirt, rust or other impairments, may exceed the force which the neutral return spring exists on the mechanism.
Accordingly, there is a need for an improved system for controlling the ground speed and direction of travel of maneuverable off-road vehicles having variable speed transmissions such as variable speed hydrostatic transmissions; which allows an operator to know by feel which direction pedal he is engaging with his foot without looking. Such a system should improve vehicle operator efficiency, in foot movement, decreasing fatigue, increasing productivity and comfort. Additionally, it would be desirable to have a foot pedal control system that provides different engaging areas for forward and reverse and which allows an operator to maintain his heel in contact with the vehicle foot rest during the disengagement of one pedal and engagement of the other.